Earthquake: shaking and trembling that results from the movement of rock beneath earth's surface Stress: a force that acts on rock to change its shape of volume Shearing: causes rock to break and slip apart or to change its shape Tension: pulls on crust, stretching rock so that it becomes thinner in the middle Compression: a stress force which squeezes rock until it folds or breaks Deformation: any change in the volume or shape of earth's crust Fault: breaks in earth's crust where slabs of crust slip past each other Strike Slip Fault: rocks on either side of the fault that slip past each other sideways with little up and down motion Normal Fault: at an angle, so one block of rock lies above the fault while the other block lies below the fault Reverse Fault: same structure as normal fault, but blocks move in opposite directions Fault Block Mountain: forms when normal fault uplift a block of rock Folds: bends in rock that forms when compression shortens and thickens parts of earth's crust Anticline: fold in rock that bends upward into an arch Syncline: fold in rock that bends downward in the middle to form a bowl Plateau: large area of flat land elevated high above sea level
Outline
Stress in the Crust
movement of earth's plate creates powerful force
Types of Stress
shearing
causes rock to break and slip apart or to change its shape
tension
makes the middle of rock thinner by stretching it
compression
squeezes rock until it folds or breaks
Kinds of Faults
faults usually occur along plate boundaries, where forces of plate motion compress, pull, or shear the crust so much that the crust breaks
strike slip fault
created by shearing
forms transform boundary between two plates
the San Andreas fault is a strike slip fault that is a transform boundary
normal fault
caused by tension
at an angle so one block of rock is above the fault while the other block lies below the fault
half of the fault that lies above is called the hanging wall
the other half of the fault is the footwall
when movement occurs, hanging wall slips downward
the Rio Grande is a rift valley where normal faults occur
reverse fault
produced by compression forces
same structure as normal fault
the Appalachian Mountains were partly produced by reverse faults
Friction Along Faults
force that is against the motion of a surface as it moves across another surface
how rocks move along a fault depends on how much friction there is between the opposite sides of the fault
Mountain Building
fault movement can change a flat plain into a towering mountain range in millions of years
mountains formed by faulting
when normal faults lift up a block of rock a fault block mountain forms
an example of a fault block mountain range is the Sierra Nevada
mountain formed by folding
two plates colliding can cause compression and folding of the crust
the Himalayas and the Alps are some of the world's largest mountain ranges
folding rocks can fracture and produce faults
anticlines and synclines
anticline
fold in rock that bends upward into an arch
Black Hills of South Dakota
syncline
fold in rock that bends downward that forms a bowl
Illinois Basin
plateaus
mountains and plateaus are raised by the same forces
Table of Contents
2.1 Earth's Crust in Motion
Vocabulary
Earthquake: shaking and trembling that results from the movement of rock beneath earth's surface
Stress: a force that acts on rock to change its shape of volume
Shearing: causes rock to break and slip apart or to change its shape
Tension: pulls on crust, stretching rock so that it becomes thinner in the middle
Compression: a stress force which squeezes rock until it folds or breaks
Deformation: any change in the volume or shape of earth's crust
Fault: breaks in earth's crust where slabs of crust slip past each other
Strike Slip Fault: rocks on either side of the fault that slip past each other sideways with little up and down motion
Normal Fault: at an angle, so one block of rock lies above the fault while the other block lies below the fault
Reverse Fault: same structure as normal fault, but blocks move in opposite directions
Fault Block Mountain: forms when normal fault uplift a block of rock
Folds: bends in rock that forms when compression shortens and thickens parts of earth's crust
Anticline: fold in rock that bends upward into an arch
Syncline: fold in rock that bends downward in the middle to form a bowl
Plateau: large area of flat land elevated high above sea level
Outline
Stress in the Crust
- movement of earth's plate creates powerful force
Types of StressKinds of Faults
- faults usually occur along plate boundaries, where forces of plate motion compress, pull, or shear the crust so much that the crust breaks
- strike slip fault
- created by shearing
- forms transform boundary between two plates
- the San Andreas fault is a strike slip fault that is a transform boundary
- normal fault
- caused by tension
- at an angle so one block of rock is above the fault while the other block lies below the fault
- half of the fault that lies above is called the hanging wall
- the other half of the fault is the footwall
- when movement occurs, hanging wall slips downward
- the Rio Grande is a rift valley where normal faults occur
- reverse fault
- produced by compression forces
- same structure as normal fault
- the Appalachian Mountains were partly produced by reverse faults
Friction Along FaultsMountain Building
Diagram